Method and apparatus for recording sounds on film



March 17, 1936. .1. F. LINDBERG f 2@33,945

METHOD AND APPARATUS FOR RECORDING SOUNDS ON FILM Original Filed Aug. 8, 19:50

DDDUUUUDEIDUDDDDEIDDDEIEIEI 2 B5 Pic/(up Davicrzv Amplifier T UUIJUIJUIJDIJDUUUU uuuuZL u nun u.u/u/11 n Am /1mm Z9 T V F Cufh'ngDev/ce. /4 /5 P/cKu n Device 27 I 7 INVENTOR John F Lind be Patented Mar. 17, 1936 UNITED 4 STATES METHOD AND AI PARATUS FOR RECORD- ING SOUNDS ON FILM John FrLindberg, Chicago, Ill., assignor to Lindberg Sound Film 00., a corporation of Illinois Application August 8, 1930, Serial No. 474,043 Renewed September 6, 1933 Claims.

This invention relates in general to a method and apparatus by means'of which sound waves, such as speech and music, for example, may be recorded on the edge of a film.

One of the objects of this invention-is the provision of apparatus and a method by means of which sound waves maybe recorded on the edge of a photographic film by cutting.

A further object of this invention is the provision of apparatus and mechanism by means of which an accurate sound record may be formed on the edge of a photographic film.

A still further object of this invention is the provision of a method of apparatus by meansof which photographic film may be softened and then cut by a suitable tool, which is caused to vibrate in accordance with and by sound waves.

A further object of this invention is the provision of means for heating the film to soften it before forming the sound record on the edge.

Another object of this invention is the provision of a cutting tool which is arranged so as to exert its force of cutting in a direction longitudinal to the length of the film as the film is moved thereby.

Another object bf this invention is the provision of a cutting tool which has a. thin cutting edge in the form of a line, and which is arranged so that its trailing edge will clear the cut film after the record is made so as not to mar the record.

These and many other objects-as will appear from the following disclosure are secured by means of this invention.

This invention resides substantially in the combination, construction, location, and relative arrangement of parts, steps and series of steps, all as will be explained in detail hereinafter.

Referring to the drawing;

Figure 1 illustrates the apparatus by means of which the film is softened and then cut to form a sound record therein;

Fig. 2 illustrates the apparatus by means of which the sound records may be reproduced;

Fig. 3 illustrates the apparatus by means of which the sound record alreadyformed on the film may be transferred or copied upon other film. Y This invention relates in general to the method and apparatus of sound recording where the sound records are cut on the thin edge of the film. Heretofore others have tried to make such sound records, but they have in general been entirely :unsatisfactory, especially from a commercial viewpoint. It has been found that the cutting edge of the tool must be in the form of a line as thin and sharp as possible. It has also been found that the best results are secured when the tool exerts a cutting force in a. direction opposite to the longitudinal movement of the film. Likewise, it has been found essential to have the trailing face of the cutting tool at such an angle with the edge of the film that it will clear the contour of the steepest angle of the sound record being cut at all times. At the same time the tool must have sufiicient thickness so as to give it the necessary strength to properly cut the film.

It has also been found that in order to get a most perfect cut with a smooth finish surface that the film be softened, preferably by heating, just before the cutting tool operates; otherwise the record will be rough or have a scraped surface, resulting 'in the production of undesirable sounds when the record is reproduced. This softening of the film permits the tool to cut the material of the film more easily with the result that its vibrations are not damped out or absorbed, with the result that a truly accurate sound record is made. These features will best be understood by detail reference to the drawing. The film which may be of the ordinary motion picture film type is indicated at I, having the sprocket perforations 2. This film may be driven in any suitable mechanism which will cause it. to have a steady unform longitudinal movement in a direction with respect to the remainder of the apparatus as indicated by the arrow. At 3 is shown the smooth uncut edge of the film and at I the edge has been shown in rough outline to diagrammatically illustrate that a sound record has been cut thereon. At 6 is the microphone or sound wave pick-up device which is connected by the wires I to a suitable amplifier 8, which may be, for example, 'of the vacuum tube type. *The output of this amplifier is connected by wires 9 to any one of a number of known types of electromagnetically operated device III. This device operates a cutting tool I l which is provided with a sharp edge of a form, for example, like a chisel. This edge has depth into the plane of the drawing so as to contact with the entire edge of the film.

As clearly shown the trailing face of the tool. H is cut away or lies at an angle so as to clear the steepest ridges or the peaks of the cut film. The shaving which is removed thereby from the film is indicated at 5. At I2 is one form of heating device by means of which the edge of the film is heated to soften it just before it reaches the cutting edge of the tool. In the form illustrated, this heater comprises a casing having a shoe, like an iron, for example, resting against the edge 3 of the film. This heater is pivotally supported at I3 and is pressed against the film by a leaf spring I4, the pressure of which on the heater maybe varied by a suitable adjustable screw or bolt l5. Within the heater casing is an electric heating coil it having one terminal connected by the wire I! to one terminal of any suitable current source l8. The other terminal of this current source is connected to any wellknown type of thermostatic device l9, which has its other terminal connected by wire 20 to the heating coil. This thermostatic device must, of course, be placed in heat relation with respect to the heater so that it will control its temperature to maintain it at a proper point to correctly heat the edge of the'film. For example, the thermostatic device can be placed directly in the heater. These parts have only been illustrated diagrammatically, since any one skilled in the art would know how to connect the parts up to make the device operable within this disclosure. In the operation of this mechanism the sound waves picked up by the microphone are amplified and delivered to the electro-magnetically actuated cutting device to cause the tool I I to vibrate by and in accordance with those sound waves. The edge of the film is heated to soften it so that it is at the proper degree of softness as it reaches the tool, so that the tool may faithfully' shave off the edge of the film to record an accurate sound record thereon. The ,film, of course, must be heated sufiiciently so that the tool may easily shave it, but at the same time the film must not be overheated, since if it is it will crystallize. For this reason the thermostatic device is provided to maintain the temperature of the heater within such limits as to properly soften the film.

The reproduction of effected by the mechanism shown in Fig. 2. The film is run through a suitable reproducer and a stylus 25 is caused to bear against the record on the edge of the film. This record causes the stylus to vibrate and set up minute electrical currents in the pick-up device 26. This pick-up device may likewise be any of the well-known types now in use. For example, both the cutting tool device In and the pick-up device 26 may be of the moving coil type. The output from the pick-up device 26 is delivered through wires 21 to a suitable amplifier 28, whose output is delivered through the wires 29 to a sound reproducer or loud speaker 30. At this point it may be well to point out that both in recording and reproducing the film, if desired, may be caused to slide between pressure plates which, while holding the film against vibration or movement in any direction transverse to its longitudinal movement, will expose the edge of the film so that the cutting tool or reproducing stylus may bear thereon.

The arrangement in Fig. 3 illustrates how a master film I which has a sound record 4 already cut thereon may be used to reproduce any number of.copies thereof. The record may be reproduced, for example, on the film l0 whichis shown with the uncut edge 4| and the cut edge 42. The output from the amplifier 28 may in this case, instead of going to the loud speaker, be delivered through wires 29 to the electro-magnetically actuated cutting device In having the tool ll. As beforethe heater with its associated parts is employed, the only difference being in this case such a sound record is a manually adjustable resistance 50 is employed in place of the thermostat for regulating the temperature of the heater.

From the foregoing disclosure it will be apparent that I have devised an apparatus which is constructed and operated in accordance with certain principles which have been illustrated in one form in the drawing. These principles may, of course, be embodied in other physical forms and I do not therefore desire to be strictly limited to the disclosure as made. Likewise, it is apparent that this invention involves a novel method of forming a sound record on the edge of a film in which the edge of the film is softened by heating. It is apparent that heating may be effected by any suitable apparatus and hence the electrical method has been shown for illustrative purposes. I prefer, therefore, to be limited by the appended claims rather than by the disclosure.

What I seek to secure by United States Letters Patent is:

1. .In a method of making a sound record on a film strip, the steps. ofmoving the film at a uniform velocity, applying heat directly to the side edge surface of the film to soften it, and cutting a sound record on the softened side edge surface of the film.

2. In the method of recording sounds on a photographic film, the steps of advancing the film at a uniform velocity, heating the side edge surface of the film by direct contact with a heat source tosoften it, vibrating a cutting tool in contact with the softened side edge surface of the surface of the film with the cutting tool to impress a sound record thereon.

3. In an apparatus for recording sound waves on theedge of a tape or film, the combination comprising a movable film, contact means for applying heat directly to the side edge surface of the film as it moves in contact therewith, and means including a thin edged cutting tool notated by and in accordance with sound waves for cutting a record of the sound waves on the edge of the .softened film as it moves, said heating means being independent of the cutting means.

4. In an apparatus for recording sound waves on the side edge surfaceof a film, the combination comprising a movable film, means for directly applying heat to the side edge of the film to soften it including ashore in contact with the edge of the film, means for controlling the heating means to maintain a substantially fixed temperature thereof, and means operating in the plane of the film and actuated by and in accordance with sound waves for cutting a sound record on the side edge surface of the softened film.

5. In an apparatus for recording sound waves on a film, the combination comprising a movable film, heating means for softening the edge of the film as it moves, a cutting tool bearing on the edge of the softened film substantially in line contact therewith, and means for causing said tool to be moved by and in accordance with sound waves to .cut a sound record on the softened edge of the film, said tool having a trailing face lying at an.

angle with the edge of the film great enough to clear the steepest cut in the record.

6. In an apparatus for recording sound waves on the edge of a film, the combination comprising a movable film, means forapplying heat directly to the side edge surface of the film to soften it, a cutting tool having an approximate line cutting edge contact with the softened edge of film by and in accordance with sound waves to be recorded, and shaving the softened side edge the film with its trailing face at an angle great enough toclear the steepest cut in the record, and means for vibrating said cutting tool in the plane of the film and by and in accordance with sound waves.

7. The method of making a sound record on a film which consists in moving the film longitudinally at a uniform speed, cutting a sound record across the entire side edge surface of the moving film, and directly heating the side edge surface of the film to soften the same in advance of the action of forming the sound record in said surface.

8. In an apparatus for recording a sound record on a film, the combination with a movable film, means arranged at the side and disposed to operate in the plane of the film and actuated by and in accordance with sound waves tocut by line contact therewith a record of the sound waves in the side edge surface of the film, and means independent of the sound record cutting means 'to heat and soften said side edge surface by the direct application of heat thereto.

9. In an apparatus for recording sound waves on a film, the combination with a movable film, a cutting tool disposed adjacent a side edge surface in line contact therewith and in the plane of the film to operate towards and from said side edge surface by and in accordance with 5 sound waves to cut a sound record entirely across said side edge surface, and means for directly applying heat to the side edge surface of the film to soften said side edge surface in advance of the action of said side record cutting means. m 10. In an apparatus for recording sound waves on the side edge of a film of the type used in motion picture apparatus, the combination with a movable film, of means for moving the film longitudinally of its length, a cutting tool hav- 15 ing a. cutting edge engageable with the side edge of the film, and means for supporting the cutting edge of said tool at a shaving angle with respect to said side edge whereby to insure the removal from said edge of film stock in the form of a 20 shaving, and means for vibrating said tool to cut a sound wave in the side edge of the film.

JOHN F. LINDBERG. 

